Modelling and simulation of state events and of structural-dynamic systems is getting more and more important in advanced modelling theory and application. Therefore, the requirements regarding flexibility on modelling and on implementation in simulators is increasing. To investigate, how modelling approaches and simulation environments deal with state events and structural-dynamic systems, the new ARGESIM Benchmark C21 ‘State Events and Structural-dynamic Systems’ is defined. Three case studies should compare modelling and implementation of state events in dynamic systems, up to structural-dynamic systems governed by state events. The first case study, the almost classical bouncing ball dynamics investigates different kinds of bounce modelling and implementation with associated events. In the second case study, Switching RLC Circuit, different diode models result in simple switching state events or in in DAE systems. The third case study is structural-dynamic by itself: the rotating pendulum with free falling phase changes dynamics from swinging to falling (an vice versa) – switching between different degrees of freedom. These three case studies invite simulationists for providing ‘solutions’ – reports on modelling, implementation and specific investigations by of suggested experiments with the implemented model, to be published in SNE Simulation Notes Europe.